The present invention relates to a polymerizable composition comprising a) at least one ethylenically unsaturated monomer and b1) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl and a free radical initiator or b2) at least one multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ether. Further aspects of the present invention are a process for polymerizing ethylenically unsaturated monomers, the (co)polymers obtainable by this process and the use of multifunctional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyls in combination with a free radical initiator, or a multi-functional triazinyl based 2,2,6,6 tetramethylpiperidine-1-oxyl-ethers for controlled polymerization.
In particular, this invention relates to stable free radical-mediated polymerization processes which provide homopolymers, random copolymers, block copolymers, multi-block copolymers, graft copolymers and the like, at enhanced rates of polymerization and enhanced monomer to polymer conversions.
U.S. Pat. No. 4,581,429 to Solomon et al., issued Apr. 8, 1986, discloses a free radical polymerization process which controls the growth of polymer chains to produce short chain or oligomeric homopolymers and copolymers, including block and graft copolymers. The process employs an initiator having the formula (in part) Rxe2x80x2Rxe2x80x3Nxe2x80x94Oxe2x80x94X, where X is a free radical species capable of polymerizing unsaturated monomers. The reactions typically have low conversion rates. Specifically mentioned radical Rxe2x80x2Rxe2x80x3Nxe2x80x94O. groups are derived from 1,1,3,3 tetraethylisoindoline, 1,1,3,3 tetrapropylisoindoline, 2,2,6,6 tetramethylpiperidine, 2,2,5,5 tetramethylpyrrolidine or di-t-butylamine. However, the suggested compounds do not fulfill all requirements. Particularly the polymerization of acrylates does not proceed fast enough and/or the monomer to polymer conversion is not as high as desired.
EP-A-735 052 discloses a method for preparing thermoplastic polymers of narrow poly-dispersities by free radical-initiated polymerization, which comprises adding a free radical initiator and a stable free radical agent to the monomer compound. However the compounds specifically disclosed therein do not fully satisfy the need of high conversion rates, which is a prerequisite for industrial scale up.
JP 08-269117 published Mar. 3, 1995 describes the polymerization of vinyl monomers with nitroxides such as the nitroxides of bis(2,2,6,6-tetramethyl-4-piperidyl) sebaic acid ester and tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4 butanetetracarboxylate.
It remains however still a problem to achieve a high conversion in short time at a low polydispersity.
The compounds of the present invention provide polymeric resin products having low polydispersity, particularly when the polymer is heated for a certain time after polymerization is completed. In addition the monomer to polymer conversion proceeds in a short time. Thus making the compounds particularly suitable for industrial polymerization processes.
One subject of the invention is a polymerizable composition, comprising
a) at least one ethylenically unsaturated monomer or oligomer, and
b) a compound of formula (I) 
xe2x80x83in which n is the number 1 or 2, and R1 is a group of the formula 
xe2x80x83in which
G1 and G2 are hydrogen, methyl or, together, are a substituent xe2x95x90O,
E is xe2x80x94Oxe2x80x94 or xe2x80x94ND3xe2x80x94,
A is C2-C6alkylene or xe2x80x94(CH2)3xe2x80x94Oxe2x80x94 and
x1 is the number 0 or 1,
D3 is hydrogen, C1-C12alkyl, C2-C5hydroxyalkyl or C5-C7cycloalkyl,
R2 is identical to R1 or is one of the groups xe2x80x94N(G21)(G22), xe2x80x94OG23, xe2x80x94N(H)(CH2OG23) or xe2x80x94N(CH2OG23)2,
R3, if n=1, is identical to R1 and,
if n=2, is an xe2x80x94Exe2x80x94D4xe2x80x94Exe2x80x94 group, in which D4 is
C2-C8alkylene or C2-C8alkylene which is interrupted by 1 or 2 xe2x80x94NG21xe2x80x94 groups,
G21 is C1-C12alkyl, cyclohexyl, benzyl or C1-C4-hydroxyalkyl or a group of the formula 
G22 is C1-C12alkyl, cyclohexyl, benzyl or C1-C4hydroxyalkyl, and
G23 is hydrogen, C1-C12alkyl or phenyl, or
G21 and G22 together are C4-C5alkylene or C4-C5oxaalkylene, for example xe2x80x94CH2CH2xe2x80x94Oxe2x80x94CH2CH2xe2x80x94, or a group of the formula xe2x80x94CH2CH2xe2x80x94N(G11)xe2x80x94CH2CH2xe2x80x94; and
G11 is O. or xe2x80x94Oxe2x80x94X, wherein
X represents a group such that the free radical X. derived from X is capable of initiating polymerization of ethylenically unsaturated monomers; and
if G11 is O., a source of free radicals is additionally present.
Some examples of the several variables in the formula (I) are given below.
Any C1-C12alkyl substituents are, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl or n-dodecyl.
Any hydroxyalkyl substituents are, for example, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.
Any C5-C7cycloalkyl substituents are, for example, cyclopentyl, cyclohexyl or cycloheptyl. Cyclohexyl is preferred.
C2-C6alkylene A is, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene or hexamethylene.
If G21, and G22 together are C4-C5alkylene or oxaalkylene, they are, for example, tetramethylene, pentamethylene or 3-oxapentamethylene.
Preferably n is 1 in formula (I).
Particularly preferred compounds of formula (I) are, wherein n is 1, R1 and R3 are a group 
and R2 is identical to R1 and R3 or is a group xe2x80x94N(G21)(G22) and the other substituents are as defined above.
Most preferred compounds of formula (I) are, wherein n is 1;
R1 and R3 are a group of formula 
xe2x80x83R2 is identical to R1 and R3, or is a group xe2x80x94N(G21)(G22),
wherein x1 is 0; G1 is hydrogen; G11 is O.; E is xe2x80x94ND3; D3 is C1-C12alkyl and G21, and G22 are independently C1-C12alkyl.
Preferably X is selected from the group consisting of xe2x80x94CH(aryl)2, xe2x80x94CH2-aryl, 
R30 is hydrogen or C1-C12alkyl;
the aryl groups are unsubstituted or substituted with C1-C12alkyl, halogen, C1-C12alkoxy, C1-C12alkylcarbonyl, glycidyloxy, OH, xe2x80x94COOH or xe2x80x94COOC1-C12alkyl.
Aryl is phenyl or naphthyl.
More preferably X is selected from the group consisting of xe2x80x94CH2-phenyl, CH3CH-phenyl, (CH3)2C-phenyl, (CH3)2CCN, xe2x80x94CH2CHxe2x95x90CH2, and CH3CHxe2x80x94CHxe2x95x90CH2.
Most preferred is a compound of formula (I), wherein G11 is xe2x80x94O.
Examples of groups of polyalkylpiperidine compounds according to formula (I) are the compounds of the following formulae: 
where R has the same meaning as in compound 74. 
where Rxe2x80x2 has the same meaning as in compound 76. 
In the above formulae G11 represents xe2x80x94O., or xe2x80x94Oxe2x80x94X, wherein X is as defined above.
Preferably the compound of formula (I) is present in an amount of from 0.01 mol-% to 30 mol-%, based on the monomer or monomer mixture, more preferably in an amount of from 0.05 mol-% to 20 mol-%, and most preferably in an amount of from 0.1 mol-% to 10 mol-% based on the monomer or monomer mixture.
The compounds according to formula (I) are in principal known and may be prepared according to standard procedures as for example described in U.S. Pat. No. 5,216,156 U.S. Pat. No. 5,004,770 or U.S. Pat. No. 5,204,473.
Preferably the source of a free radical initiator is a bis-azo compound, a peroxide or a hydroperoxide.
More preferably, the source of free radicals is 2,2xe2x80x2-azobisisobutyronitrile, 2,2xe2x80x2-azobis(2-methyl-butyronitrile), 2,2xe2x80x2-azobis(2,4-dimethylvaleronitrile), 2,2xe2x80x2-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1xe2x80x2-azobis(1-cyclohexanecarbonitrile), 2,2xe2x80x2-azobis(isobutyramide) dihydrate, 2-phenylazo-2,4-dimethyl-4-methoxyvaleronitrile, dimethy-2,2xe2x80x2-azobisisobutyrate, 2-(carbamoylazo)isobutyronitrile, 2,2xe2x80x2-azobis(2,4,4-trimethylpentane), 2,2xe2x80x2-azobis(2-methylpropane), 2,2xe2x80x2-azobis(N,Nxe2x80x2-dimethyleneisobutyramidine), free base or hydrochloride, 2,2xe2x80x2-azobis(2-amidinopropane), free base or hydrochloride, 2,2xe2x80x2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)ethyl]propionamide} or 2,2xe2x80x2-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide.
Preferred peroxides and hydroperoxides are acetyl cyclohexane sulphonyl peroxide, diisopropyl peroxy dicarbonate, t-amyl perneodecanoate, t-butyl perneodecanoate, t-butyl perpivalate, t-amylperpivalate, bis(2,4-dichlorobenzoyl)peroxide, diisononanoyl peroxide, didecanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, bis (2-methylbenzoyl) peroxide, disuccinic acid peroxide, diacetyl peroxide, dibenzoyl peroxide, t-butyl per 2-ethylhexanoate, bis-(4-chlorobenzoyl)-peroxide, t-butyl perisobutyrate, t-butyl permaleinate, 1,1-bis(t-butylperoxy)3,5,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, t-butyl peroxy isopropyl carbonate, t-butyl perisononaoate, 2,5-dimethylhexane 2,5-dibenzoate, t-butyl peracetate, t-amyl perbenzoate, t-butyl perbenzoate, 2,2-bis (t-butylperoxy) butane, 2,2 bis (t-butylperoxy) propane, dicumyl peroxide, 2,5-dimethylhexane-2,5-di-t-butylperoxide, 3-t-butylperoxy 3-phenylphthalide, di-t-amyl peroxide, xcex1, xcex1xe2x80x2-bis(t-butylperoxy isopropyl) benzene, 3,5-bis (t-butylperoxy)3,5-dimethyl 1,2-dioxolane, di-t-butyl peroxide, 2,5-dimethylhexyne-2,5-di-t-butylperoxide, 3,3,6,6,9,9-hexamethyl 1,2,4,5-tetraoxa cyclononane, p-menthane hydroperoxide, pinane hydroperoxide, diisopropylbenzene mono-xcex1-hydroperoxide, cumene hydroperoxide or t-butyl hydroperoxide.
Preferably the radical source, generating the free radical initiator is present in an amount of from 0.01 mol % to 30 mol %.
Preferably when G11 is xe2x80x94O. the molar ratio of the free radical source to the compound of formula I is from 1:2 to 20:1, more preferably from 1:1 to 5:1.
Preferably the ethylenically unsaturated monomer or oligomer is selected from the group consisting of alkene, styrene, substituted styrene, conjugated dienes, acrolein, vinyl acetate, (alkyl)acrylic acidanhydrides, (alkyl)acrylic acid salts, (alkyl)acrylic esters or (alkyl)acrylamides.
More preferably the ethylenically unsaturated monomer is ethylene, propylene, n-butylene, i-butylene, isoprene, 1,3-butadiene, xcex1-C5-C18alkene, styrene, xcex1-methyl styrene, p-methyl styrene or a compound of formula CH2xe2x95x90C(Ra)xe2x80x94(Cxe2x95x90Z)xe2x80x94Rb, wherein Ra is hydrogen or C1-C4alkyl, Rb is NH2, O(Me), glycidyl, unsubstituted C1-C18alkoxy, C1-C18alkoxy interrupted by at least one N and/or O atom, or hydroxy-substituted C1-C18alkoxy, C1-C18alkoxy interrupted by at least one N and/or O atom, unsubstituted C1-C18alkylamino, di(C1-C18alkyl)amino, hydroxy-substituted C1-C18alkylamino or hydroxy-substituted di(C1-C18alkyl)amino, xe2x80x94Oxe2x80x94CH2xe2x80x94CH2xe2x80x94N(CH3)2 or xe2x80x94Oxe2x80x94CH2xe2x80x94CH2xe2x80x94N+H(CH3)2 Anxe2x88x92;
An is a anion of a monovalent organic or inorganic acid;
Me is a monovalent metal atom
Z is oxygen or sulfur.
Particularly preferred are monomers, wherein Ra is hydrogen, Rb is NH2, unsubstituted or with hydroxy substituted C1-C4alkoxy, unsubstituted C1-C4alkylamino, di(C1-C4alkyl)amino, hydroxy-substituted C1-C4alkylamino or hydroxy-substituted di(C1-C4alkyl)amino; and Z is oxygen.
Most preferably the ethylenically unsaturated monomer is styrene, xcex1-methyl styrene or p-methyl styrene and ethylene.
To increase polymerization rate furthermore, organic sulfonic or organic carboxylic acids (U.S. Pat. No. 5,322,912), sulfonic acid salts (U.S. Pat. No. 5,608,023), acid anhydrides (Malmstrxc3x6m, E.; Miller, R. D.; Hawker, C. J. Tetrahedron 1997, 53, 15225-15236) or vinyl monomers containing acid groups (WO 96/18663) can be added to the polymerization process. Furthermore, the polymerization rate can be enhanced by the addition of phosphorous compounds (U.S. Pat. No. 5,610,249), electron accepting compounds (EP 0 773 232), dimethylsulfoxide (U.S. Pat. No. 5,412,012), reducing agents (EP 0 897 930) or metal catalysts and stable free radical complex catalysts (U.S. Pat. No. 5,744,560).
Another subject of the present invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the monomer or monomers/oligomers in the presence of a compound of formula (I) as described above, wherein if
G1 is xe2x80x94Oxe2x80x94X
a) under reaction conditions capable of effecting scission of the Oxe2x80x94X bond to form two free radicals, the radical .X being capable of initiating polymerization; or if
G11 is O.
b) additionally in the presence of a free radical source, liberating a free radical which is capable of initiating polymerization.
Preferred is a process, wherein the scission of the Oxe2x80x94X bond is effected by ultrasonic treatment, heating or exposure to electromagnetic radiation, ranging from xcex3 to microwaves. More preferred is a process, wherein the scission of the Oxe2x80x94X bond is effected by heating and takes place at a temperature of between 50xc2x0 C. and 180xc2x0 C.
Preferred is a process, wherein the polymerization takes place at a temperature between 50xc2x0 and 180xc2x0 C., more preferred at a temperature between 110xc2x0 and 150xc2x0 C.
A further subject of the invention is a process for preparing an oligomer, a cooligomer, a polymer or a copolymer (block or random) by free radical polymerization of at least one ethylenically unsaturated monomer or oligomer, which comprises (co)polymerizing the monomer or monomers/oligomers in the presence of
a) a compound having at least two 
xe2x80x83groups, under reaction conditions capable of effecting scission of the Oxe2x80x94X bond to form two free radicals, the radicals .X being capable of initiating polymerization and the radicals 
xe2x80x83being stable free nitroxyl radicals or
b) an initiator/regulator compound having at least two stable free nitroxyl radicals 
xe2x80x83and additionally a free radical source is present; and
wherein after polymerization is completed at least one additional heating step at a temperature from 140xc2x0 to 280xc2x0 C. is applied.
Examples of suitable compounds are those of Formula (I) and the compounds given below.
Nitroxyl-ethers having at least two 
groups and nitroxyl radicals having at least two stable nitroxyl groups 
suitable for the above process are for example compounds of the formula (II) 
in which n1 is a number from 2 to 4, G and G1, independently of one another, are hydrogen or methyl,
G11 is O. or Oxe2x80x94X
G12, if n1 is 2, is C2-C12alkylene, C4-C12alkenylene, xylylene, a divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, dicarbamic acid or phosphorus-containing acid or a divalent silyl radical, preferably a radical of an aliphatic dicarboxylic acid having 2 to 36 carbon atoms, or a cycloaliphatic or aromatic dicarboxylic acid having 8-14 carbon atoms or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 carbon atoms, where each dicarboxylic acid may be substituted in the aliphatic, cycloaliphatic or aromatic moiety by one or two xe2x80x94COOZ12 groups,
G12, if n1 is 3, is a trivalent radical of an aliphatic, cycloaliphatic or aromatic tricarboxylic acid, which may be substituted in the aliphatic, cycloaliphatic or aromatic moiety by xe2x80x94COOZ12, of an aromatic tricarbamic acid or of a phosphorus-containing acid, or is a trivalent silyl radical,
and G12, if n1 is 4, is a tetravalent radical of an aliphatic, cycloaliphatic or aromatic tetracarboxylic acid.
Alkyl with up to 20 carbon atoms is, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.